Injection type internal combustion engines



June 27, 1967 OERTEL 3,327,691 INJECTION TYPE INTERNAL COMBUSTION ENGINES Filed Jan. 22, 1965 United States Patent 3,327,691 INJECTION TYPE INTERNAL COMBUSTION ENGINES Erhard Oertel, Ruhstortf, near Passau, Germany, assignor to Motorenfabrik Hatz G.m.b.H., Ruhstorf, near Passau, Germany, a German company Filed Jan. 22, 1965, Ser. No. 427,270

Claims priority, application Germany, Jan. 29, 1964,

M 59,729 1 Claim. (Cl. 123-32) This invention relates to an injection type internal combustion engine, and particularly to such engines having a cylinder head fabricated of light metal such as aluminum or aluminum alloys and having a whirl chamber associated with the injection nozzle.

It is an object of this invention to provide a simple and effective structure for such an engine to prevent excessive heat transfer directly between the whirl chamber and the cylinder head, and consequently also to make possible the use of a cylinder head made of a light metal for air cooled engines. In accordance with the invention this object is achieved by providing a structure wherein the whirl chamber, in the area facing the piston working space in the cylinder, is formed by a potshaped insert member having in its floor an exit opening leading to the piston working space, the insert being made of a material of low heat conductivity and being insertably mounted in the cylinder head in the proper angular position. Preferably the insert member is made of a heat proof, superior alloy or refined steel which is resistant to oxidation, and is inserted with a light wringing or twist fit in a receiving bore of the cylinder head. The light wringing fit of the insert member in the cylinder head results in avoiding possible stresses or cracks .in the cylinder head during assembly.

In the preferred embodiment of the invention, the insert member is formed as a pot-shaped casing with a substantially fiat floor facing the piston head and having an arched opening therein which extends obliquely relative to the cylinder axis. Such an insert member can be formed as a casting, and will require only little finishing, thus rendering its production economical.

Preferably the insert member is grooved along its outer circumference in order to create a gap between the receiving bore of the cylinder head and the circumferential surface of the insert member, this insulating gap serving to reduce heat transfer between the insert member and the cylinder head.

The insert member in accordance with the invention is secured axially in the receiving bore inside the cylinder head by positioning the receiving bore so as to overlap a porton of the mating surface of the cylinder block, and the insert member accordingly will be embraced between the cylinder block and a portion of the cylinder head. Further, the insert member is so formed as to engage positively a correspondingly formed portion of the cylinder block, thus securing the insert member against any possible rotational movement in the receiving bore of the cylinder head.

Other and further objects, advantages and features of the invention will be apparent to those skilled in the art from the following description taken with reference to the accompanying drawings of preferred embodiments of the invention, wherein:

FIGURE 1 is a sectioned elevation view of a cylinder head and block embodying some features of the invention, the section being taken along the line I--l of FIGURE 3;

FIGURE 2 is a sectional view taken along line II-II of FIGURE 3;

FIGURE 3 is a plan view in section of FIGURE 1, the section being taken along line III--III of FIGURE 1;

FIGURE 4 is a sectioned fragmentary view of an insert member constructed in accordance with the invention;

FIGURE 5 is a top view of FIGURE 4.

Referring in more detail to FIGURES 1-3, the cylinder head 1 of a single-cylinder four-stroke cycle internal combustion engine consists of a casting of a light metal such as aluminum or an aluminum base alloy, the bottom surface of the cylinder head being finished flat in order to mate with a corresponding surface of the cylinder block 2 which accommodates the piston 3. Four attaching bolts, not shown, each of which passes through a bore 1b in the head 1, will connect the cylinder head 1 and the cylinder block 2. The suction and exhaust pipes (not shown) are connected respectively to the flanges 4a and 4b of the head 1. The corresponding channels in the cylinder head have been designated by 5a and 5b. The valves (not shown) for the engine are mounted with their shafts guided in b-ores 6a and 6b, and counter sinkings 7a and 7b are provided to accommodate valve seats (not shown) which are press fit therein. For accommodating an injection nozzle (not shown) of a known type, there is provided a graduated bore or chamber 8 which leads to a hemispherical whirl chamber space 9 which leads to the piston working space or cylinder.

At the circumference of the cylinder head 1 a number of vertically positioned cooling flanges 10 are provided. These flanges are formed as parts of the integral casting. Through these cooling flanges and the casing 11 which surrounds them, several axial channels extend along the periphery of the cylinder head. The cooling flanges 10 and the casing 11 mate with corresponding formations on the cylinder block 2 so that the axial channels of the head 1 will communicate with corresponding axial channels along the periphery of the cylinder block 2. An additional channel 12 is formed in the cylinder head in the vicinity of the valves and the injection nozzle where the highest thermal stresses normally exist. Channel 12 is divided into two branches 12a and 12b which communicate with corresponding axial passages at 13. Channel 12 is further divided into two channels by a longitudinal rib member 14, and these channels terminate in two openings at the lower side of the cylinder head 1, which openings communicate with corresponding passages formed in the cylinder block 2. These last mentioned passages conveniently are connected to the exhaust system of the internal combustion engine so that the cooling air will be induced to flow through the channel 12 in the direction of the arrows shown in FIGURES 1 and 2.

The whirl chamber space 9 is formed as a hemispherical hollow space adjoining the injection nozzle, which hollow space is formed in the body of the head during the production process. The whirl chamber space is separated from the piston 3 by a pot-shaped insert member 15, which has in its bottom floor an arched obliquely extending exit opening 15a, while a groove 15b extends around its pheriphery between two cylindrical end centering surfaces. The insert member is made of heat resistant, superior alloy or refined steel, and its end entering surfaces are dimensioned diametrically so as to be received in the receiving bore with a light wringing or twist fit. Thus the exit opening 15a of the insert member will always maintain the correct angular position in relation to the slightly inclined impact surface 3a which is formed in the piston 3. As shown in FIGURE 1, the insert member 15 is secured axially through a small overlap with a portion of the cylinder block 2.

The cylindrical wall of the pot-shaped insert memher 15, which is relatively insensitive to heat, forms the greater part of the periphery of the whirl chamber in the cylinder head. Thus the insulating effect of the cylindrical wallof the insert member and the hollow gap which is formed by the groove 15b reduce the direct heat transfer between the very hot gases which develop during operation in the whirling chamber and the cylinder head 1.

The light wringing fit between the insert member 15 and the receiving bore of the cylinder head permits replacement of the insert member without any substantial difiiculty if, for instance, the opening 15a should become partially closed by carbonization. Also, this light wringing fit ensures that no stresses or cracks will develop in the cylinder head during assembly.

FIGURES 4 and 5 show a design in accordance with the invention. Here the insert member has an arched formation 15c on the end thereof adjacent the piston 3, which arched formation forms arcuate shoulders to abut corresponding portions of the cylinder block 2 and the cylinder Wall. In this manner the insert member 15 is positively prevented from moving either axially or rotationally, and this design permits one to utilize a looser fit between the insert member and the receiving bore of the cylinder head. Otherwise the embodiment of FIGURES 4 and 5 is identical to the embodiment of FIGURES 1-3.

The invention renders possible a single whirl cham oer with a fiat impact floor and a slanting exit opening in a cylinder head fabricated from light metal, such as aluminum or aluminum alloys. Engines constructed in accordance with the invention display a relative insensitivity to high speeds, as well as good cold-starting qualities.

The cylinder heads of engines constructed in accordance with the invention can be fabricated of any of numerous nonferrous light metals, the most common of which are aluminum and aluminum base alloys. The insert member should be fabricated from a metal of relatively low thermal conductivity such as superior alloy or refined steel. Suitable steels will be apparent to those skilled in the art. For instance, two suitable examples are listed in the German Steel Industry List as No. 4873 and No. 4885, which are refined steels of very high heat resistance having melting points between 800 and 1l50 centigrade. The metals are thus very stable at high temperatures. The steels which are numbered 4878 and 4885 are produced, for instance, by the company Deutsche Edelstahlwerke AG, Krefeld, Germany, under the respective names Thermax 8A and Thermax l1 AST.

Having thus described my invention in the manner required by the patent statutes, I claim:

In an air-cooled injection-type internal combustion engine, a cylinder block having a cylinder opening therefrom; a cylinder head mounted on said cylinder block and closing one end of said cylinder, said cylinder head being for-med of a light metal; a nozzle chamber formed in said cylinder head for accommodating an injection nozT zle; a receiving bore formed in said cylinder head .in communication with said nozzle chamber and opening into said cylinder at one end; an insert member insertably mounted in said receiving bore with a light wringing fit and shaped to form a whirl chamber, said insert member having an opening formed therein to communicate said whirl chamber with said cylinder, said insert member being formed of a refined steel of low thermal conductivity; and means forming arcuate shoulders on said insert member to abut the cylinder Wall and the face of the cylinder block to secure said insert member against rotational movement about its axis.

References Cited UNITED STATES PATENTS 2,795,215 6/1957 Holt 123-32 2,821,177 1/1958 Holt 123-32 2,985,155 5/1961 Hockel 12332.-8 3,089,471 5/ 1963 Espenschied 123-328 3,259,116 7/1966 Bricout 123-32 MARK NEWMAN, Primary Examiner.

LAURENCE M. GOODRIDGE, Examiner. 

